柴达木盆地西部地层的风力侵蚀对黄土高原物源贡献的研究进展

Research progress of the lacustrine strata deflation for western Qaidam Basin and its provenance significance for Chinese Loess Plateau

中文关键词:  风力侵蚀  湖相沉积  柴达木盆地西部地区  物源  黄土高原

英文关键词:wind erosion  lacustrine strata  western Qaidam Basin  provenance  Chinese Loess Plateau

中文摘要:

      柴达木盆地是我国西北地区最干旱的盆地之一,常年盛行强劲的西北风,尤其在冬春季更甚。柴达木盆地西部地区自新生代以来沉积了巨厚的河湖相沉积。自上新世晚期以来,随着气候的逐步干化和盆地内部构造变形的加剧,该地区风力侵蚀地貌开始出现。早更新时出现的古盐壳和古雅丹地貌说明当时侵蚀已经相当剧烈。晚更新时以来,气候的极端干旱化和冰期的出现,更加促进了风蚀地貌的发育,在强劲的低空风力的雕刻下,形成了盆地西部几万平方千米的“百万雅丹”地貌,十分壮观。柴达木盆地不同地区风蚀地层的厚度和速率都不同,最大可达3 km和1.1 mm/yr,如此巨量的物质搬运必然为下风向的地区(都兰、青海湖地区、西宁盆地、黄土高原)的粉尘堆积提供可观的物源物质。研究表明,柴达木盆地西部被侵蚀的古湖相地层是上述地区,尤其是黄土高原重要的物源物质。随着研究的深入,其盆地内侵蚀物质输送到黄土高原的机制,已被学界越来越清晰的认识。

英文摘要:

      Qaidam Basin is one of the most arid basins in the western China and dominated by the strong northwest wind, especially in winter and spring. Thousands kilometers thick lacustrine and fluvial sedimentary have been deposited in the basin since Cenozoic. However, initiation of the late Pliocene, it appeared the wind erosion in the western Qaidam Basin with the aridification of palaeoclimate and intensity of the tectonic deformation. The forming of palaeo-salt-crust and palaeo-yardangs indicated the deflation is rather drastic in later period. With the deteriorating of palaeoclimate and emerging of glacial periods since late Pleistocene, and strong wind sculpture the vast lacustrine sediments in western Qaidam Basin and then development of mega-yardangs landform. The thick of deflated strata and erosion rate in the basin are different, the most thickness reach to 3 kilometers and erosion rate is 1.1 mm/yr. So much deflated materials transportation must contribute the abundant dust to the downwind areas such as Dulan, Qinghai Lake, Xining area as well as Chinese Loess Plateau. Previous studies show that the Qaidam Basin is the one of most important source areas for aeolian deposit in Chinese Loess Plateau, this understanding is more and more accepted by Quaternary community.